CASE REPORT
Large esophageal schwannoma mimicking thyroid tumor with egg-shell calcification on preoperative ultrasonography
Dongbin Ahn a,*, Jin Ho Sohn a, Heejin Kim a, Chang Ki Yeo b
aDepartment of OtolaryngologydHead and Neck Surgery, School of Medicine, Kyungpook National University, Daegu, Korea
bDepartment of OtolaryngologydHead and Neck Surgery, School of Medicine, Keimyung University, Daegu, Korea
Received 1 October 2013; accepted 24 April 2014 Available online 14 June 2014
KEYWORDS dysphagia;
esophagus;
schwannoma;
thyroid;
ultrasonography
Summary Schwannoma tumors in esophagus are extremely rare and clinically present as dysphagia in most reported cases. Because of their rarity and need for histopathological confir- mation using immunohistochemistry, an erroneous diagnostic and therapeutic approach can be adopted. A 36-year-old woman presented at the hospital with complaints of an anterior neck mass. On ultrasonography, a large left thyroid mass with egg-shell calcification was suspected.
However, the thyroid surgeon found that it was not a thyroid tumor. An incision biopsy was per- formed for histopathological analysis, which revealed a schwannoma. Then, salivary leakage occurred through the cervical incision site, suggesting that the incisional biopsy had caused esophageal perforation. She was transferred to our department and underwent emergency sur- gery. We successfully resected the tumor and controlled the infection without any further injury to the esophagus, although it was a revision surgery and the wound was greatly infected.
We believe that it is important to always keep in mind that an atypical presentation of esoph- ageal schwannoma may lead to the development of, for example, a large nodule in the left thyroid gland involving the esophagus.
ª 2017 Asian Surgical Association and Taiwan Robotic Surgical Association. Publishing services by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://
creativecommons.org/licenses/by-nc-nd/4.0/).
Conflicts of interest: All authors declare no conflicts of interest.
* Corresponding author. Department of OtolaryngologydHead and Neck Surgery, Kyungpook National University Medical Center, 807 Hogukno, Buk-gu, Daegu 702-210, Korea.
E-mail address:[email protected](D. Ahn).
http://dx.doi.org/10.1016/j.asjsur.2014.04.002
1015-9584/ª 2017 Asian Surgical Association and Taiwan Robotic Surgical Association. Publishing services by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Available online atwww.sciencedirect.com
ScienceDirect
j ourna l homepa ge: www.e-asianj ourna lsurge ry .com Asian Journal of Surgery (2017) 40, 236e239
1. Introduction
Esophageal schwannoma is extremely rare. Since it was first reported by Chaterlin and Fissore1in 1967, only 30 articles on esophageal schwannoma have been published in Eng- lish.2e7Because of its rarity and difficulty in diagnosis until histopathological examination of a surgical specimen, esophageal schwannoma is hardly ever considered in pa- tients with a large mass located at the lower anterior neck.
Other tumors originating from the thyroid gland, the thymus, or the lymph node are considered.
Herein, we report the case of a large esophageal schwannoma mimicking a thyroid tumor on preoperative ultrasonography (US), resulting in iatrogenic esophageal perforation.
2. Case Report
The patient was a 36-year-old woman who initially pre- sented with a history of progressive anterior neck mass that had lasted several months. The patient had mild dysphagia, but was able to consume a regular diet. The patient visited our hospital (but not our department) and underwent neck US. On the US, a large mass with egg-shell calcification was identified in the left thyroid gland, presenting posterior acoustic shadowing (Fig. 1). There was no abnormal lymph node in the bilateral cervical region. The patient was evaluated according to the guidelines issued by the Amer- ican Thyroid Association under the clinical impression of a large thyroid nodule, and underwent fine needle aspiration and thyroid function test. The result of fine needle aspi- ration was reported as atypia with undetermined signifi- cance, and thyroid-stimulating hormone level was within normal range. Thyroidectomy was planned to confirm the thyroid malignancy and manage her discomfort. However, after thyroidectomy, the thyroid surgeon found that the tumor was not originating from the thyroid gland. It was
located posterior to the thyroid gland, compressing the thyroid gland anteriorly. On the basis of this finding, the thyroid surgeon did not perform complete excision of the mass; instead, an incisional biopsy was performed for his- topathological diagnosis analysis. Histopathology revealed schwannoma. Seven days after initial surgery, the patient was referred to our department in a poor clinical condition.
The patient was unable to eat or drink. Salivary leakage through the cervical incision site was occurring since Post- operative Day 2, suggesting that incisional biopsy had caused esophageal perforation. The wound was greatly infected and foul smelling. To determine the tumor size and extent of infection, computed tomography (CT) and mag- netic resonance imaging (MRI) were performed. On CT scan, the tumor was identified as located in the cervical esoph- agus, displacing the trachea to the right side and obstructing the esophageal lumen (Fig. 2A). Collection of saliva was found, and severe inflammation was noted. On coronal MRI, a fusiform tumor of approximately 6.5 cm in size, which extended to the substernal area, was identified (Fig. 2B). We planned surgical exploration to control the infection causing the abscess and to excise the tumor completely as soon as possible because more severe adhesion was anticipated if further delay was introduced.
During surgery, we first identified the recurrent laryngeal nerve, which ran along the esophagus, and the perforation site at the esophagus. A large tumor was palpated at the posteromedial aspect of the cervical esophagus. With best effort to preserve mucosal integrity of the esophagus, we attempted to expose the tumor, which was located within the submucosal plane of the esophagus. After peeling the tumor off the esophageal wall laterally and superiorly, we could completely dissect the tumor, including its substernal portion, by pulling it superiorly without sternotomy (Fig. 3).
The esophageal perforation sitedthe result of the previous incisional biopsydwas closed primarily and reinforced with an inferior-based sternocleidomastoid muscle rotation flap.
On gross inspection, the tumor was well capsulated and was 6.5 cm 4.5 cm in size. The cut surface of the tumor appeared homogenous yellow (similar to the appearance of a typical schwannoma), but there was no calcification (Fig. 4). Pathologic examination confirmed a benign schwannoma. A barium swallow study on Postoperative Day 4 revealed that there was no leakage. The patient started oral intake of a soft diet. The patient was allowed to resume a regular diet on Postoperative Day 7. At the 1-year follow-up, the patient was well without any complications.
3. Discussion
Unlike in previous reports of esophageal schwannoma, our patient’s chief complaint was anterior neck mass rather than dysphagia. Of the approximately 30 case reports on esophageal schwannoma, in only one report the chief complaint of the esophageal schwannoma was palpable neck mass as well as dysphagia.7 In our case, tolerable swallowing despite a large esophageal mass was possibly due to the tumor’s characteristic of indolent growth and elasticity of the esophagus. Therefore, US was used as the first imaging modality for neck mass, rather than endo- scopic examination for esophageal lesion. On US, the mass Figure 1 On initial ultrasonography, a large mass with egg-
shell calcification was identified in the left thyroid gland, presenting posterior acoustic shadowing.
Esophageal schwannoma mimicking thyroid tumor 237
appeared to be a thyroid tumor with egg-shell calcification occupying almost the entire left thyroid gland. Interest- ingly, however, echogenicity of the esophagus was not found on that image. The radiologist might have considered that it was due to posterior acoustic shadow of egg-shell calcification or compression of esophagus by the tumor.
Unfortunately, once thyroid nodule was suspected as the causative lesion of the neck mass, additional imaging mo- dalities, such as CT or MRI, were not performed because US alone is widely accepted as a diagnostic imaging tool for thyroid nodule, and none of the guidelines issued by the American Thyroid Association and American Association of Clinical Endocrinologists/Associazione Medici Endo- crinologi/European Thyroid Association recommend the routine use of CT, MRI, and positron emission tomography for evaluating thyroid nodules.8,9However, in review of the initial US image obtained, we suggest that the hyper- echogenic lining that appeared within the left thyroid gland
was not egg-shell calcification of the tumor, but mucosal lining of the esophagus, which was anteriorly displaced by the esophageal tumor. In fact, we did not find any calcified lesion within the tumor on macro- and microscopic exami- nations of the specimen.
Because benign schwannoma is a submucosal tumor, the tumor was excised completely without perforation of the esophagus or performing esophagectomy in almost all re- ported cases.2,3,5e7 However, in the present case, tumor excision was very challenging because curative surgery for esophageal schwannoma was performed as a revision sur- gery, and the wound was greatly infected. Nevertheless, we successfully resected the tumor and controlled the infec- tion without any further injury to the esophagus, after making the decision of immediate surgical exploration.
In a review of the literature, only one Czech report was found in which esophageal schwannoma was misdiagnosed as a thyroid tumor preoperatively, as in our case.10 Although esophageal schwannoma is extremely rare, the surgeon can collect the necessary clinical information for differential diagnosis if sufficient imaging studies are per- formed. It is important to always keep in mind that an atypical presentation of esophageal schwannoma may lead Figure 2 (A) Neck computed tomography scan shows a large esophageal mass (asterisk) dislocating the trachea to the right side and nasogastric tube to the left side. Collection of leaked saliva and severe inflammation are suggested. (B) Coronal T2 magnetic resonance imaging reveals a 6.5-cm fusiform tumor extending to the substernal area.
Figure 3 After peeling the tumor off the esophageal wall laterally and superiorly, we could completely dissect the tumor, including its substernal portion, by pulling it superiorly, while identifying and preserving the recurrent laryngeal nerve (arrow).
Figure 4 Cut surface of the tumor appeared homogeneously yellow, similar to a typical schwannoma, but no calcified tissue (suspected on the preoperative ultrasonography) is observed.
238 D. Ahn et al.
to the development of, for instance, a large nodule in the left thyroid gland involving the esophagus.
References
1.Chaterlin C, Fissore A. Schwanome degenere de l’esophage.
Confront Radio Anat Clin. 1967;7:114 [in French].
2.Dutta R, Kumar A, Jindal T, Tanveer N. Concurrent benign schwannoma of oesophagus and posterior mediastinum.
Interact Cardiovasc Thorac Surg. 2009;9:1032e1034.
3.George M, Augustine AM, Mathew J, Cherian VT, Cherian VK.
Ancient schwannoma of the oesophagus presenting with stri- dor: case report. J Laryngol Otol. 2009;123:1384e1386. 4.Kassis ES, Bansal S, Perrino C, et al. Giant asymptomatic primary
esophageal schwannoma. Ann Thorac Surg. 2012;93:e81ee83. 5.Marin VP, Yu P, Weber RS. Isolated cervical esophageal recon-
struction for rare esophageal tumors. Head Neck. 2006;28:
856e860.
6.Matsuki A, Kosugi S, Kanda T, et al. Schwannoma of the esophagus: a case exhibiting high 18F-fluorodeoxyglucose up- take in positron emission tomography imaging. Dis Esophagus.
2009;22:E6eE10.
7.Yoon HY, Kim CB, Lee YH, Kim HG. An obstructing large schwannoma in the esophagus. J Gastrointest Surg. 2008;12:
761e763.
8.Cooper DS, Doherty GM, Haugen BR, et al. Revised American Thyroid Association management guidelines for patients with thyroid nodules and differentiated thyroid cancer. Thyroid.
2009;19:1167e1214.
9.Gharib H, Papini E, Paschke R, et al. American Association of Clinical Endocrinologists, Associazione Medici Endocrinologi, and European Thyroid Association medical guidelines for clin- ical practice for the diagnosis and management of thyroid nodules. Endocr Pract. 2010;16(Suppl 1):1e43.
10.Duskova J, Bures E, Svobodova E. Neurilemmoma of the esophagus imitating carcinoma of the thyroid isthmus. Cesk Patol. 1993;29:22e25.
Esophageal schwannoma mimicking thyroid tumor 239
